Generating dynamic modular proxies

ABSTRACT

A runtime environment generates a proxy class in response to detecting a request for a proxy object. The proxy class implements a set of interfaces specified by the request for the proxy object. The runtime environment selects or generates a proxy module, in a module system, to include the proxy class. The runtime environment exposes interfaces from other modules to the proxy module using a qualified export that does not expose the interfaces to modules other than the proxy module. The runtime environment does not expose the proxy class, of the proxy module, to other modules in the module system.

BENEFIT CLAIM; INCORPORATION BY REFERENCE

This application claims benefit to provisional application No.62/215,535 filed on Sep. 8, 2015, the contents of which are herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to dynamic proxies. In particular, thepresent disclosure relates to generating dynamic module proxies forwhite-box testing.

BACKGROUND

A module system permits the definition of a set of modules. Each modulein a module system corresponds to a respective collection of code. Amodule system specifies how a collection of code corresponding to aparticular module can access code corresponding to other modules. Amodule descriptor, for a particular module, expresses other modules uponwhich the particular module may depend. The declaration of a dependencyon another module may be referred to as an explicit dependency. A moduledescriptor also expresses the elements of a particular module that areexposed by the particular module to the other modules. These othermodules declare an explicit dependency on the particular module withinrespective descriptors. Other modules which do not declare an explicitdependency on the particular module are restricted from accessing theelements of the particular module.

A proxy class in a particular module of the module system cannotimplement interfaces in other modules that have not been exposed to theparticular module. If the proxy class is located in a same module as afirst non-exposed publicly accessible interface, the proxy class mayimplement the first non-exposed publicly accessible interface. However,that proxy class cannot implement a second non-exposed publiclyaccessible interface within a second different module than the proxyclass.

The approaches described in this section are approaches that could bepursued, but not necessarily approaches that have been previouslyconceived or pursued. Therefore, unless otherwise indicated, it shouldnot be assumed that any of the approaches described in this sectionqualify as prior art merely by virtue of their inclusion in thissection.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments are illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings. It should benoted that references to “an” or “one” embodiment in this disclosure arenot necessarily to the same embodiment, and they mean at least one. Inthe drawings:

FIG. 1 illustrates an example computing architecture in which techniquesdescribed herein may be practiced.

FIG. 2 is a block diagram illustrating one embodiment of a computersystem suitable for implementing methods and features described herein.

FIG. 3 illustrates an example virtual machine memory layout in blockdiagram form according to an embodiment.

FIGS. 4A and 4B illustrate examples of one or more module systems inaccordance with one or more embodiments.

FIGS. 5A and 5B illustrate operations in accordance with one or moreembodiments.

FIG. 6 illustrates a system in accordance with one or more embodiments.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding. One or more embodiments may be practiced without thesespecific details. Features described in one embodiment may be combinedwith features described in a different embodiment. In some examples,well-known structures and devices are described with reference to ablock diagram form in order to avoid unnecessarily obscuring the presentinvention.

-   -   1. GENERAL OVERVIEW    -   2. ARCHITECTURAL OVERVIEW        -   2.1 EXAMPLE CLASS FILE STRUCTURE        -   2.2 EXAMPLE VIRTUAL MACHINE ARCHITECTURE        -   2.3 LOADING, LINKING, AND INITIALIZING    -   3. MODULE ELEMENTS OF A MODULE IN A MODULE SYSTEM    -   4. GENERATING DYNAMIC MODULAR PROXIES    -   5. MISCELLANEOUS; EXTENSIONS    -   6. HARDWARE OVERVIEW

1. General Overview

One or more embodiments include a runtime environment (a) generating aproxy class within a particular module of a module system and (b)exposing interfaces of other modules to the particular module of themodule system. In one embodiment, the runtime environment exposes atleast two interfaces in two other respective modules to the particularmodule that includes the proxy class using a qualified export. The atleast two interfaces may have been module-private interfaces that hadnot been exposed to any modules in the module system prior to theruntime environment exposing the interfaces to the particular modulethat includes the proxy class. The runtime environment uses a qualifiedexport to expose the at least two interfaces to the particular modulethat includes the proxy class without exposing the at least twointerfaces to any modules other than the particular module in the modulesystem.

The particular module, which includes the proxy class, may be (a)generated by the runtime environment or (b) selected by the runtimeenvironment from a set of modules already defined by the module system.In an embodiment, the runtime environment does not expose the proxyclass, in the particular module, to other modules in the module system.Not exposing the proxy class includes not exposing any module element(e.g., package), of the particular module, which includes the proxyclass.

In an embodiment, the runtime environment generates the proxy class inresponse to a request for a proxy object. In an example, the runtimeenvironment identifies a request for a proxy object from a set of modulecode (“test framework”) in a test framework module. The request for theproxy object includes a set of class objects representing interfaces anda method call processor object. The request may further include a classloader. The runtime environment generates a proxy class that implementseach of the interfaces represented by the class objects and returns aproxy object of the proxy class to the requesting test framework module.The test framework traverses/tests the methods of the interfacesimplemented by the proxy class at least in part by executing reflectiveoperations on the proxy object.

One or more embodiments described in this Specification and/or recitedin the claims may not be included in this General Overview section.

2. Architectural Overview

FIG. 1 illustrates an example architecture in which techniques describedherein may be practiced. Software and/or hardware components describedwith relation to the example architecture may be omitted or associatedwith a different set of functionality than described herein. Softwareand/or hardware components, not described herein, may be used within anenvironment in accordance with one or more embodiments. Accordingly, theexample environment should not be constructed as limiting the scope ofany of the claims.

As illustrated in FIG. 1, a computing architecture 100 includes sourcecode files 101 which are compiled by a compiler 102 into blueprintsrepresenting the program to be executed. Examples of the blueprintsinclude class files 103. The class files 103 are then loaded andexecuted by an execution platform 112, which includes a runtimeenvironment 113, an operating system 111, and one or more applicationprogramming interfaces (APIs) 110 that enable communication between theruntime environment 113 and the operating system 111. The runtimeenvironment 112 includes a virtual machine 104 comprising variouscomponents, such as a memory manager 105 (which may include a garbagecollector), a class file verifier 106 to check the validity of classfiles 103, a class loader 107 to locate and build in-memoryrepresentations of classes, an interpreter 108 for executing the virtualmachine 104 code, and a just-in-time (JIT) compiler 109 for producingoptimized machine-level code.

In an embodiment, the computing architecture 100 includes source codefiles 101 that contain code that has been written in a particularprogramming language, such as Java, C, C++, C#, Ruby, Perl, and soforth. Thus, the source code files 101 adhere to a particular set ofsyntactic and/or semantic rules for the associated language. Forexample, code written in Java adheres to the Java LanguageSpecification. However, since specifications are updated and revisedover time, the source code files 101 may be associated with a versionnumber indicating the revision of the specification to which the sourcecode files 101 adhere. The exact programming language used to write thesource code files 101 is generally not critical.

In various embodiments, the compiler 102 converts the source code, whichis written according to a specification directed to the convenience ofthe programmer, to either machine or object code, which is executabledirectly by the particular machine environment, or an intermediaterepresentation (“virtual machine code/instructions”), such as bytecode,which is executable by a virtual machine 104 that is capable of runningon top of a variety of particular machine environments. The virtualmachine instructions are executable by the virtual machine 104 in a moredirect and efficient manner than the source code. Converting source codeto virtual machine instructions includes mapping source codefunctionality from the language to virtual machine functionality thatutilizes underlying resources, such as data structures. Often,functionality that is presented in simple terms via source code by theprogrammer is converted into more complex steps that map more directlyto the instruction set supported by the underlying hardware on which thevirtual machine 104 resides.

In general, programs are executed either as a compiled or an interpretedprogram. When a program is compiled, the code is transformed globallyfrom a first language to a second language before execution. Since thework of transforming the code is performed ahead of time; compiled codetends to have excellent run-time performance. In addition, since thetransformation occurs globally before execution, the code can beanalyzed and optimized using techniques such as constant folding, deadcode elimination, inlining, and so forth. However, depending on theprogram being executed, the startup time can be significant. Inaddition, inserting new code would require the program to be takenoffline, re-compiled, and re-executed. For many dynamic languages (suchas Java) which are designed to allow code to be inserted during theprogram's execution, a purely compiled approach may be inappropriate.When a program is interpreted, the code of the program is readline-by-line and converted to machine-level instructions while theprogram is executing. As a result, the program has a short startup time(can begin executing almost immediately), but the run-time performanceis diminished by performing the transformation on the fly. Furthermore,since each instruction is analyzed individually, many optimizations thatrely on a more global analysis of the program cannot be performed.

In some embodiments, the virtual machine 104 includes an interpreter 108and a JIT compiler 109 (or a component implementing aspects of both),and executes programs using a combination of interpreted and compiledtechniques. For example, the virtual machine 104 may initially begin byinterpreting the virtual machine instructions representing the programvia the interpreter 108 while tracking statistics related to programbehavior, such as how often different sections or blocks of code areexecuted by the virtual machine 104. Once a block of code surpass athreshold (is “hot”), the virtual machine 104 invokes the JIT compiler109 to perform an analysis of the block and generate optimizedmachine-level instructions which replaces the “hot” block of code forfuture executions. Since programs tend to spend most time executing asmall portion of overall code, compiling just the “hot” portions of theprogram can provide similar performance to fully compiled code, butwithout the start-up penalty. Furthermore, although the optimizationanalysis is constrained to the “hot” block being replaced, there stillexists far greater optimization potential than converting eachinstruction individually. There are a number of variations on the abovedescribed example, such as tiered compiling.

In order to provide clear examples, the source code files 101 have beenillustrated as the “top level” representation of the program to beexecuted by the execution platform 111. Although the computingarchitecture 100 depicts the source code files 101 as a “top level”program representation, in other embodiments the source code files 101may be an intermediate representation received via a “higher level”compiler that processed code files in a different language into thelanguage of the source code files 101. Some examples in the followingdisclosure assume that the source code files 101 adhere to a class-basedobject-oriented programming language. However, this is not a requirementto utilizing the features described herein.

In an embodiment, compiler 102 receives as input the source code files101 and converts the source code files 101 into class files 103 that arein a format expected by the virtual machine 104. For example, in thecontext of the JVM, the Java Virtual Machine Specification defines aparticular class file format to which the class files 103 are expectedto adhere. In some embodiments, the class files 103 contain the virtualmachine instructions that have been converted from the source code files101. However, in other embodiments, the class files 103 may containother structures as well, such as tables identifying constant valuesand/or metadata related to various structures (classes, fields, methods,and so forth).

The following discussion assumes that each of the class files 103represents a respective “class” defined in the source code files 101 (ordynamically generated by the compiler 102/virtual machine 104). However,the aforementioned assumption is not a strict requirement and willdepend on the implementation of the virtual machine 104. Thus, thetechniques described herein may still be performed regardless of theexact format of the class files 103. In some embodiments, the classfiles 103 are divided into one or more “libraries” or “packages”, eachof which includes a collection of classes that provide relatedfunctionality. For example, a library may contain one or more classfiles that implement input/output (I/O) operations, mathematics tools,cryptographic techniques, graphics utilities, and so forth. Further,some classes (or fields/methods within those classes) may include accessrestrictions that limit their use to within a particularclass/library/package or to classes with appropriate permissions.

2.1 Example Class File Structure

FIG. 2 illustrates an example structure for a class file 200 in blockdiagram form according to an embodiment. In order to provide clearexamples, the remainder of the disclosure assumes that the class files103 of the computing architecture 100 adhere to the structure of theexample class file 200 described in this section. However, in apractical environment, the structure of the class file 200 will bedependent on the implementation of the virtual machine 104. Further, oneor more features discussed herein may modify the structure of the classfile 200 to, for example, add additional structure types. Therefore, theexact structure of the class file 200 is not critical to the techniquesdescribed herein. For the purposes of Section 2.1, “the class” or “thepresent class” refers to the class represented by the class file 200.

In FIG. 2, the class file 200 is made up of class members including, butnot limited to, a constant table 201, field structures 208, classmetadata 204, and method structures 209. In an embodiment, the constanttable 201 is a data structure which, among other functions, acts as asymbol table for the class. For example, the constant table 201 maystore data related to the various identifiers used in the source codefiles 101 such as type, scope, contents, and/or location. The constanttable 201 has entries for value structures 202 (representing constantvalues of type int, long, double, float, byte, string, and so forth),class information structures 203, name and type information structures205, field reference structures 206, and method reference structures 207derived from the source code files 101 by the compiler 102. In anembodiment, the constant table 201 is implemented as an array that mapsan index i to structure j. However, the exact implementation of theconstant table 201 is not critical.

In some embodiments, the entries of the constant table 201 includestructures which index other constant table 201 entries. For example, anentry for one of the value structures 202 representing a string may holda tag identifying its “type” as string and an index to one or more othervalue structures 202 of the constant table 201 storing char, byte or intvalues representing the ASCII characters of the string.

In an embodiment, field reference structures 206 of the constant table201 hold an index into the constant table 201 to one of the classinformation structures 203 representing the class defining the field andan index into the constant table 201 to one of the name and typeinformation structures 205 that provides the name and descriptor of thefield. Method reference structures 207 of the constant table 201 hold anindex into the constant table 201 to one of the class informationstructures 203 representing the class defining the method and an indexinto the constant table 201 to one of the name and type informationstructures 205 that provides the name and descriptor for the method. Theclass information structures 203 hold an index into the constant table201 to one of the value structures 202 holding the name of theassociated class.

The name and type information structures 205 hold an index into theconstant table 201 to one of the value structures 202 storing the nameof the field/method and an index into the constant table 201 to one ofthe value structures 202 storing the descriptor.

In an embodiment, class metadata 204 includes metadata for the class,such as version number(s), number of entries in the constant pool,number of fields, number of methods, access flags (whether the class ispublic, non-public, final, abstract, etc.), an index to one of the classinformation structures 203 of the constant table 201 that identifies thepresent class, an index to one of the class information structures 203of the constant table 201 that identifies the superclass (if any), andso forth.

In an embodiment, the field structures 208 represent a set of structuresthat identifies the various fields of the class. The field structures208 store, for each field of the class, accessor flags for the field(whether the field is static, public, non-public, final, etc.), an indexinto the constant table 201 to one of the value structures 202 thatholds the name of the field, and an index into the constant table 201 toone of the value structures 202 that holds a descriptor of the field.

In an embodiment, the method structures 209 represent a set ofstructures that identifies the various methods of the class. The methodstructures 209 store, for each method of the class, accessor flags forthe method (e.g. whether the method is static, public, non-public,synchronized, etc.), an index into the constant table 201 to one of thevalue structures 202 that holds the name of the method, an index intothe constant table 201 to one of the value structures 202 that holds thedescriptor of the method, and the virtual machine instructions thatcorrespond to the body of the method as defined in the source code files101.

In an embodiment, a descriptor represents a type of a field or method.For example, the descriptor may be implemented as a string adhering to aparticular syntax. While the exact syntax is not critical, a fewexamples are described below.

In an example where the descriptor represents a type of the field, thedescriptor identifies the type of data held by the field. In anembodiment, a field can hold a basic type, an object, or an array. Whena field holds a basic type, the descriptor is a string that identifiesthe basic type (e.g., “B”=byte, “C”=char, “D”=double, “F”=float,“I”=int, “J”=long int, etc.). When a field holds an object, thedescriptor is a string that identifies the class name of the object(e.g. “L ClassName”). “L” in this case indicates a reference, thus “LClassName” represents a reference to an object of class ClassName. Whenthe field is an array, the descriptor identifies the type held by thearray. For example, “[B” indicates an array of bytes, with “[”indicating an array and “B” indicating that the array holds the basictype of byte. However, since arrays can be nested, the descriptor for anarray may also indicate the nesting. For example, “[[L ClassName”indicates an array where each index holds an array that holds objects ofclass ClassName. In some embodiments, the ClassName is fully qualifiedand includes the simple name of the class, as well as the pathname ofthe class. For example, the ClassName may indicate where the file isstored in the package, library, or file system hosting the class file200.

In the case of a method, the descriptor identifies the parameters of themethod and the return type of the method. For example, a methoddescriptor may follow the general form “({ParameterDescriptor})ReturnDescriptor”, where the {ParameterDescriptor} is a list of fielddescriptors representing the parameters and the ReturnDescriptor is afield descriptor identifying the return type. For instance, the string“V” may be used to represent the void return type. Thus, a methoddefined in the source code files 101 as “Object m (int I, double d,Thread t) { . . . }” matches the descriptor “(I D L Thread) L Object”.

In an embodiment, the virtual machine instructions held in the methodstructures 209 include operations which reference entries of theconstant table 201. Using Java as an example, consider the followingclass:

class A { int add12and13( ) {     return B.addTwo(12, 13);     } }

In the above example, the Java method add12and13 is defined in class A,takes no parameters, and returns an integer. The body of methodadd12and13 calls static method addTwo of class B which takes theconstant integer values 12 and 13 as parameters, and returns the result.Thus, in the constant table 201, the compiler 102 includes, among otherentries, a method reference structure that corresponds to the call tothe method B.addTwo. In Java, a call to a method compiles down to aninvoke command in the bytecode of the JVM (in this case invokestatic asaddTwo is a static method of class B). The invoke command is provided anindex into the constant table 201 corresponding to the method referencestructure that identifies the class defining addTwo “B”, the name ofaddTwo “addTwo”, and the descriptor of addTwo “(I I)I”. For example,assuming the aforementioned method reference is stored at index 4, thebytecode instruction may appear as “invokestatic #4”.

Since the constant table 201 refers to classes, methods, and fieldssymbolically with structures carrying identifying information, ratherthan direct references to a memory location, the entries of the constanttable 201 are referred to as “symbolic references”. One reason thatsymbolic references are utilized for the class files 103 is because, insome embodiments, the compiler 102 is unaware of how and where theclasses will be stored once loaded into the runtime environment 112. Aswill be described in Section 2.3, eventually the run-time representationof the symbolic references are resolved into actual memory addresses bythe virtual machine 104 after the referenced classes (and associatedstructures) have been loaded into the runtime environment and allocatedconcrete memory locations.

2.2 Example Virtual Machine Architecture

FIG. 3 illustrates an example virtual machine memory layout 300 in blockdiagram form according to an embodiment. In order to provide clearexamples, the remaining discussion will assume that the virtual machine104 adheres to the virtual machine memory layout 300 depicted in FIG. 3.In addition, although components of the virtual machine memory layout300 may be referred to as memory “areas”, there is no requirement thatthe memory areas are contiguous.

In the example illustrated by FIG. 3, the virtual machine memory layout300 is divided into a shared area 301 and a thread area 307. The sharedarea 301 represents an area in memory where structures shared among thevarious threads executing on the virtual machine 104 are stored. Theshared area 301 includes a heap 302 and a per-class area 303. In anembodiment, the heap 302 represents the run-time data area from whichmemory for class instances and arrays is allocated. In an embodiment,the per-class area 303 represents the memory area where the datapertaining to the individual classes are stored. In an embodiment, theper-class area 303 includes, for each loaded class, a run-time constantpool 304 representing data from the constant table 201 of the class,field and method data 306 (for example, to hold the static fields of theclass), and the method code 305 representing the virtual machineinstructions for methods of the class.

The thread area 307 represents a memory area where structures specificto individual threads are stored. In FIG. 3, the thread area 307includes thread structures 308 and thread structures 311, representingthe per-thread structures utilized by different threads. In order toprovide clear examples, the thread area 307 depicted in FIG. 3 assumestwo threads are executing on the virtual machine 104. However, in apractical environment, the virtual machine 104 may execute any arbitrarynumber of threads, with the number of thread structures scaledaccordingly.

In an embodiment, thread structures 308 includes program counter 309 andvirtual machine stack 310. Similarly, thread structures 311 includesprogram counter 312 and virtual machine stack 313. In an embodiment,program counter 309 and program counter 312 store the current address ofthe virtual machine instruction being executed by their respectivethreads.

Thus, as a thread steps through the instructions, the program countersare updated to maintain an index to the current instruction. In anembodiment, virtual machine stack 310 and virtual machine stack 313 eachstore frames for their respective threads that hold local variables andpartial results, and is also used for method invocation and return.

In an embodiment, a frame is a data structure used to store data andpartial results, return values for methods, and perform dynamic linkingA new frame is created each time a method is invoked. A frame isdestroyed when the method that caused the frame to be generatedcompletes. Thus, when a thread performs a method invocation, the virtualmachine 104 generates a new frame and pushes that frame onto the virtualmachine stack associated with the thread.

When the method invocation completes, the virtual machine 104 passesback the result of the method invocation to the previous frame and popsthe current frame off of the stack. In an embodiment, for a giventhread, one frame is active at any point. This active frame is referredto as the current frame, the method that caused generation of thecurrent frame is referred to as the current method, and the class towhich the current method belongs is referred to as the current class.

2.3 Loading, Linking, and Initializing

In an embodiment, the virtual machine 104 dynamically loads, links, andinitializes classes. Loading is the process of finding a class with aparticular name and creating a representation from the associated classfile 200 of that class within the memory of the runtime environment 112.For example, creating the run-time constant pool 304, method code 305,and field and method data 306 for the class within the per-class area303 of the virtual machine memory layout 300. Linking is the process oftaking the in-memory representation of the class and combining it withthe run-time state of the virtual machine 104 so that the methods of theclass can be executed. Initialization is the process of executing theclass constructors to set the starting state of the field and methoddata 306 of the class and/or create class instances on the heap 302 forthe initialized class.

The following are examples of loading, linking, and initializingtechniques that may be implemented by the virtual machine 104. However,in many embodiments the steps may be interleaved, such that an initialclass is loaded, then during linking a second class is loaded to resolvea symbolic reference found in the first class, which in turn causes athird class to be loaded, and so forth. Thus, progress through thestages of loading, linking, and initializing can differ from class toclass. Further, some embodiments may delay (perform “lazily”) one ormore functions of the loading, linking, and initializing process untilthe class is actually required. For example, resolution of a methodreference may be delayed until a virtual machine instruction invokingthe method is executed. Thus, the exact timing of when the steps areperformed for each class can vary greatly between implementations.

To begin the loading process, the virtual machine 104 starts up byinvoking the class loader 107 which loads an initial class. Thetechnique by which the initial class is specified will vary fromembodiment to embodiment. For example, one technique may have thevirtual machine 104 accept a command line argument on startup thatspecifies the initial class.

To load a class, the class loader 107 parses the class file 200corresponding to the class and determines whether the class file 200 iswell-formed (meets the syntactic expectations of the virtual machine104). If not, the class loader 107 generates an error. For example, inJava the error might be generated in the form of an exception which isthrown to an exception handler for processing. Otherwise, the classloader 107 generates the in-memory representation of the class byallocating the run-time constant pool 304, method code 305, and fieldand method data 306 for the class within the per-class area 303.

In some embodiments, when the class loader 107 loads a class, the classloader 107 also recursively loads the super-classes of the loaded class.For example, the virtual machine 104 may ensure that the superclasses ofa particular class are loaded, linked, and/or initialized beforeproceeding with the loading, linking and initializing process for theparticular class.

During linking, the virtual machine 104 verifies the class, prepares theclass, and performs resolution of the symbolic references defined in therun-time constant pool 304 of the class.

To verify the class, the virtual machine 104 checks whether thein-memory representation of the class is structurally correct. Forexample, the virtual machine 104 may check that each class except thegeneric class Object has a superclass, check that final classes have nosub-classes and final methods are not overridden, check whether constantpool entries are consistent with one another, check whether the currentclass has correct access permissions for classes/fields/structuresreferenced in the constant pool 304, check that the virtual machine 104code of methods will not cause unexpected behavior (e.g. making sure ajump instruction does not send the virtual machine 104 beyond the end ofthe method), and so forth. The exact checks performed duringverification are dependent on the implementation of the virtual machine104. In some cases, verification may cause additional classes to beloaded, but does not necessarily require those classes to also be linkedbefore proceeding. For example, assume Class A contains a reference to astatic field of Class B. During verification, the virtual machine 104may check Class B to ensure that the referenced static field actuallyexists, which might cause loading of Class B, but not necessarily thelinking or initializing of Class B. However, in some embodiments,certain verification checks can be delayed until a later phase, such asbeing checked during resolution of the symbolic references. For example,some embodiments may delay checking the access permissions for symbolicreferences until those references are being resolved.

To prepare a class, the virtual machine 104 initializes static fieldslocated within the field and method data 306 for the class to defaultvalues. In some cases, setting the static fields to default values maynot be the same as running a constructor for the class. For example, theverification process may zero out or set the static fields to valuesthat the constructor would expect those fields to have duringinitialization.

During resolution, the virtual machine 104 dynamically determinesconcrete memory address from the symbolic references included in therun-time constant pool 304 of the class. To resolve the symbolicreferences, the virtual machine 104 utilizes the class loader 107 toload the class identified in the symbolic reference (if not alreadyloaded). Once loaded, the virtual machine 104 has knowledge of thememory location within the per-class area 303 of the referenced classand its fields/methods. The virtual machine 104 then replaces thesymbolic references with a reference to the concrete memory location ofthe referenced class, field, or method. In an embodiment, the virtualmachine 104 caches resolutions to be reused in case the sameclass/name/descriptor is encountered when the virtual machine 104processes another class. For example, in some cases, class A and class Bmay invoke the same method of class C. Thus, when resolution isperformed for class A, that result can be cached and reused duringresolution of the same symbolic reference in class B to reduce overhead.

In some embodiments, the step of resolving the symbolic referencesduring linking is optional. For example, an embodiment may perform thesymbolic resolution in a “lazy” fashion, delaying the step of resolutionuntil a virtual machine instruction that requires the referencedclass/method/field is executed.

During initialization, the virtual machine 104 executes the constructorof the class to set the starting state of that class. For example,initialization may initialize the field and method data 306 for theclass and generate/initialize any class instances on the heap 302created by the constructor. For example, the class file 200 for a classmay specify that a particular method is a constructor that is used forsetting up the starting state. Thus, during initialization, the virtualmachine 104 executes the instructions of that constructor.

In some embodiments, the virtual machine 104 performs resolution onfield and method references by initially checking whether thefield/method is defined in the referenced class. Otherwise, the virtualmachine 104 recursively searches through the super-classes of thereferenced class for the referenced field/method until the field/methodis located, or the top-level superclass is reached, in which case anerror is generated.

3. Module Elements of a Module in a Module System

One or more embodiments are applicable to a module system. Each modulewithin a module system corresponds to a respective set of code (referredto as “module code”). Each module is associated with one or more moduleelements. A module element, as referred to herein, corresponds to aportion of the module code. A module element (portion of module code)may itself include additional module elements (sub-portions of modulecode).

Module systems implemented in different programming languages may bedefined with different types of module elements. Some examples,described herein, refer to the specific module elements of a module in aJava Module System for purposes of explanation. However, embodiments areequally applicable to module elements of different types in modulesystems implemented in other programming languages.

In the Java Module System, each module includes one or more packages.Each package includes one or more blueprints representing programs to beexecuted. An example of a blueprint is a class. Each class includes oneor more class members such as fields and methods. Methods, as referredto herein, include constructors which may be invoked for the creation ofan object by instantiating classes. A module element, as referred toherein with respect to the Java Module System, may include a package, aclass, or a class member. Examples of module elements include but arenot limited to an interface and a proxy class that implements theinterface.

Exposing Module Elements

In an embodiment, a particular module of the module system may attemptto access a module element of another module of the module system. Themodule attempting the access is referred to herein as a consumer moduleand the module with the module element being accessed is referred toherein as a provider module. A module may function as either a consumermodule or provider module for different access operations. A moduleelement of a provider module must be exposed to a consumer module inorder for the consumer module to successfully access the module elementof the provider module.

In an embodiment, the module element, of the provider module, is exposedto the consumer module if any of a set of conditions are met. The set ofconditions may include, but are not limited to (a) a declaration withinthe descriptor of the second module code that exposes the module elementto the first module code via a qualified or unqualified export, (b) auser instruction received via a control mechanism (e.g., a command lineinterface), (c) a determination by the run-time environment based ondetection of a triggering event associated with permissions for exposingthe module element, and (d) receipt of any instruction that instructs amodule system to expose the module element of the provider module to theconsumer module.

In an example, a package may be exposed by a provider module when amodule descriptor, corresponding to the provider module, includes an“exports” expression with the package identified as a parameter. Thepackage may be exported to a set of specified modules (referred to as“qualified export”) or to all other modules in the module system(referred to as “unqualified export”).

A particular module element may be exposed by exposing of the particularmodule element itself or by exposing another module element whichincludes the particular module element. In one example, a class may beexposed by exposing a package which includes the class. Class members ofthe class are also exposed by exposing of the package which includes theclass.

Access Modifiers for Module Elements

In an embodiment, a module element is declared with an access modifier.The access modifier expresses an accessibility configuration of themodule element. The accessibility configuration declares whether or notthe module element is publicly accessible. In one example, the modifier“public” indicates that a module element is publicly accessible and themodifier “private” indicates that the module element is not publiclyaccessible.

In an embodiment, an access modifier which declares a module element asnot publicly accessible may be overridden by setting an accessibilityconfiguration override (e.g., by invoking the setAccessible( ) method ofthe Java reflection API). The accessibility configuration overrideconfigures the module element (with the not publicly accessibleconfiguration) as if the module element were declared with anaccessibility configuration declaring the module element publiclyaccessible.

Access to Module Elements

As noted above, a module element of a provider module (1) may or may notbe exposed to a consumer module and (2) may or may not be a publiclyaccessible module element. The module element of a provider module isaccessible to a different consumer module if:

-   -   (a) the module element has been exposed to the consumer module;        and    -   (b) the module element is publicly accessible (either by the        access modifier declaring the module element as publicly        accessibly or by the accessibility configuration override        setting the module element as publicly accessible).

In an example, a module element of a provider module is declared aspublicly accessible. The module element is exposed to a first consumermodule but not exposed to a second consumer module. The first consumermodule may access the module element of the provider module. However,the second consumer module is prohibited from accessing the moduleelement of the provider module.

4. Generating Dynamic Modular Proxies

FIGS. 4A and 4B illustrate examples of one or more module systems inaccordance with one or more embodiments. Other embodiments may includemore or less modules than illustrated in FIGS. 4A and 4B. Furthermore,modules in other embodiments may include more, less, and/or differentmodule dependencies and/or module elements than described below.Accordingly, the scope of the claims should not be construed as beinglimited by the specific examples herein.

FIG. 4A illustrates a particular state of a module system. Asillustrated in FIG. 4A, the particular state of the module systemincludes a test framework module 430. A test framework module is anymodule that includes a set of code (“test framework”) to test theinterfaces of modules in the module system. Modules 410-420 representany number of modules, each with one or more interfaces (e.g.,interfaces A-N) that are to be tested by the set of code in the testframework module 430. The set of code, while illustrated in a separatetest framework module (i.e., test framework module 430), may instead beincluded in one of the modules with interfaces being tested.

In an embodiment, each of the interfaces A-N of modules 410-420 isexposed to the test framework module 430. Exposing each of theinterfaces A-N of modules 410-420 may be performed by exposing ofpackages in each of modules 410-420 that include interfaces A-N.

The exposing of the interfaces A-N to the test framework module 430 inthe particular illustrated state of FIG. 4A may instead be completed ina different state of the module system (e.g., a second state of themodule system as illustrated in FIG. 4B when the interfaces A-N areexposed to the proxy module 402). Furthermore, any other set of code(e.g., standard application code) in any other module (e.g., a standardapplication module) may be implemented instead of the test framework inthe test framework module 430. The test framework module 430 isspecifically referenced and described in detail for purposes ofexplanation and clarity.

In an embodiment, FIG. 4B illustrates a second state of the modulesystem. In the second state of the module system, a runtime environmenthas created proxy class 404 that implements interfaces A-N. In oneexample, a proxy class (defined in the Java reflection API) is a classcreated at runtime that implements a specified list of interfaces, knownas proxy interfaces. A proxy object is an instance of a proxy class.Each proxy object has an associated method call processor object. Anexample of a method call processor object is an invocation handlerobject, which implements the interface InvocationHandler. A methodinvocation on a proxy object through one of its proxy interfaces will bedispatched to the invoke method of the instance's invocation handler,passing the proxy object, a java.lang.reflect.Method object identifyingthe method that was invoked, and an array of type Object containing thearguments. The invocation handler processes the encoded methodinvocation as appropriate and the result that it returns will bereturned as the result of the method invocation on the proxy object.

In an embodiment, the proxy class 404 is in a particular module, i.e.,proxy module 402. A proxy module, as referred to herein, is any modulethat includes the proxy class 404. In an embodiment, in the second stateof the module system, the runtime environment has exposed each of theinterfaces A-N from modules 410-420 to the proxy module 402.

Operations for a runtime environment to (a) generate the proxy class 404in a proxy module 402 and (b) expose the interfaces of other modules tothe proxy module, as illustrated in FIG. 4B, are described below indetail with reference to FIGS. 5A and 5B.

Other embodiments may include more, less, and/or different operationsthan the operations described below with reference to FIGS. 5A and 5B.Furthermore, other embodiments may execute the operations in a differentorder than described below. Other embodiments may include a differentset of code, unrelated to a testing framework, configured for performingone or more of the operations described below. Accordingly, the specificoperations, order thereof, or performer thereof should not be construedas limiting the scope of any of the claims.

FIG. 5A illustrates an example set of operations performed by a set ofcode (“test framework”) in a test framework module. The set ofoperations performed by the test framework result in the runtimeenvironment generating the proxy class in a proxy module as describedbelow with reference to FIG. 5B.

Initially, a test framework obtains a set of class objects representinginterfaces that have been exposed to the test framework (Operation 502).The test framework may receive the class objects (representinginterfaces) as arguments from the ultimate consumer code. The testframework may create the class objects (representing interfaces) viajava.lang.ClassLoader.loadClass method that loads the bytes of .classfile from disk and then defines classes to the virtual machine, e.g. viathe defineClass method of java.lang.ClassLoader. The test framework maycreate the class objects (representing interfaces) indirectly, using theJava reflection API. For example, the test framework may invoke thejava.lang.Class.forName(String className) method which returns the Classobject associated with the class or interface identified in thearguments of the method.

In an embodiment, the test framework obtains a method call processorobject (Operation 504). The test framework may instantiate a classimplementing a method call processor to obtain the method call processorobject. In an example, the test framework instantiates a user-definedclass myInvocationHandler which implements an interfaceInvocationHandler in the Java reflection API. The test framework mayreceive the method call processor object as an argument from theultimate consumer code. The test framework may create the method callprocessor object via java.lang.ClassLoader.loadClass method that loadsthe bytes of myInvocationHandler.class file from disk and then definesclasses to the virtual machine, e.g. via the defineClass method ofjava.lang.ClassLoader. The test framework may create the method callprocessor object indirectly, using the Java reflection API.

In an embodiment, the test framework requests a proxy object based onthe class objects (representing the interfaces) and the method callprocessor object (Operation 506). Requesting the proxy object mayinclude invoking a method with parameters (a) an array of the classobjects (representing the interfaces and (b) the method call processorobject. The method invocation may further specify a particular classloader as a parameter. In an example, the test framework requests aproxy object from the proxy subsystem by invoking the newInstance methodof java.lang.reflect.Proxy and passing at least (a) an array of theclass objects representing the interfaces and (b) an object ofmyInvocationHandler type.

The test framework obtains the proxy object from the runtime environmentas a result of the request for the proxy object in accordance with oneor more embodiments (Operation 508). The creation of the proxy object bythe runtime environment is described in detail below with reference toFIG. 5B.

In an embodiment, the test framework uses the proxy object to invoke themethods of the interfaces (Operation 520). The test framework may usereflective operations (e.g., from the Java reflection API) to invoke themethods of the interfaces. Even though the test framework is able toobtain the proxy object from the runtime environment, the test frameworkcannot itself instantiate the proxy class because the proxy class (in aproxy module) has not been exposed to the test framework module thatincludes the test framework.

In an example, the test framework may use the following code set(expressed in pseudocode) to request a proxy object and invoke themethods of interfaces using reflective operations executed on the proxyobject:

Object o = { request to make proxy object } Class c = o.getClass( );//get proxy class of proxy object Class[ ] is = c.getInterfaces( );//array of class objects representing interfaces for (Class i : is) {//traverse all interfaces   Method[ ] ms = i.getMethods( ) // array ofmethods for the interface   for (Method m : ms) { //traverse each methodof the interface     m.invoke(random arguments)    //invoke methods fortesting   } }

Referring now to FIG. 5B, the creation of the proxy class and the proxyobject are described below with reference to Operations 510-518. Theruntime environment identifies the request from the test framework, forthe proxy object, that includes as parameters: (a) an array of classobjects representing interfaces and (b) a method class processor object(Operation 510). As noted above, the request for the proxy object mayfurther include a class loader as a parameter. The runtime environmentdetects the request during the execution of the test framework. Theproxy class, to-be-instantiated to create the proxy object, does notexist when the request for the proxy object is detected by the runtimeenvironment.

In an embodiment, the runtime environment generates a proxy class that(a) implements all of the interfaces represented by the class objects inthe request for the proxy object and (b) uses the method call processorobject to help to implement the methods of the interfaces. (Operation512). The runtime environment identifies the declarations of theinterfaces based on the class objects that represent the interfaces. Theruntime environment generates a proxy class using the declarations ofthe interfaces.

In an example, each of the declarations of the interfaces A-N mayinclude but are not limited to the structural elements as illustratedbelow with reference to interface A, each interface having any number ofrespective methods:

interface A {    void a_Method1( );    ...    void a_MethodAM( ); //AMis the total number of methods in    interface A }

The proxy class which is generated by the runtime environment and whichimplements each of the interfaces A-N may include but is not limited toone or more structured elements as illustrated below:

class $Proxy$ implements A-N //name of proxy class selected by runtimeenvironment {    // methods of interface A    void a_Method1( ){...Invoke ‘a_Method1’ on method call processor...}    void a_Method2( ){... Invoke ‘a_Method2’ on method call processor...}    ...    voida_MethodAM( ) {... Invoke ‘a_MethodAM’ on method call processor...}   //AM is the total number of methods of interface A    // methods ofinterface B    void b_Method1( ) {... Invoke ‘b_Method1’ on method callprocessor...}    void b_Method2( ) {... Invoke ‘b_Method2’ on methodcall processor...}    ...    void b_MethodBM( ) {... Invoke ‘b_MethodBM’on method call processor...}    //BM is the total number of methods ofinterface B    ...    // methods of interface N    void n_Method1( ){... Invoke ‘n_Method1’ on method call processor...}    void n_Method2() {... Invoke ‘n_Method2’ on method call processor...}    ...    voidn_methodNM( ) {... Invoke ‘n_MethodNM’ on method call processor...}   //NM is the total number of methods of interface N    } }

In an embodiment, an access modifier declaring whether or not the proxyclass is publicly accessible is determined based on accessibilityconfiguration of the interfaces and/or whether the interfaces areexposed to other modules.

In an embodiment, the runtime environment (a) generates a new proxymodule that is to include the proxy class or (b) selects an existingmodule defined by the module system as a proxy module to include theproxy class (Operation 514). In at least one embodiment, the runtimeenvironment does not expose the proxy class in the proxy module to anyother module in the module system.

In one example, a new proxy module is always generated for the proxyclass. In another example, the proxy class is always added to anexisting module. In yet another example, the generation or selection ofthe proxy module depends on accessibility configuration of theinterfaces and/or whether the interfaces are exposed to other modules.

In an embodiment, the runtime environment exposes all of the interfaces(in respective modules), that are to be implemented by the proxy class,to the proxy module which includes the proxy class (Operation 516). Inan example, the runtime environment exposes the interfaces to the proxymodule by modifying the descriptors of the modules which include theinterfaces. Specifically, the runtime environment may modify thedescriptor of a module to expose the interface to the proxy module. Inanother example, the runtime environment may expose the interfaces tothe proxy module without modifying the descriptors of the modules whichinclude the interfaces. In this example, the runtime environment mayexpose the interfaces to the proxy module by updating a data setindicating which module elements (e.g., interfaces) of one or moremodules are exposed to the proxy module. This data set is used by theruntime environment to determine which module elements of a providermodule are exposed to which consumer module.

In an embodiment, the runtime environment instantiates the proxy classto generate a proxy object and returns the proxy object to therequesting test framework (Operation 518). Instantiating the proxyobject may include invoking a constructor for the proxy class. Theconstructor may be defined by the runtime environment or accessed from apredefined API.

In one example, the interfaces to be tested include at least twoparticular interfaces in two different respective modules. The twoparticular interfaces are declared with access modifiers declaring theinterfaces to be publicly accessible. However, the particular interfacesare not exposed by respective modules to any of the other modules in themodule system. As a result, each of the two particular interfaces are“module private” and accessible only to the module elements within thesame module as the interfaces. Conventionally, a proxy class would notbe able to implement a non-exposed interface in a different module thanthe proxy class. Even if the proxy class was in a same module as one ofthe two particular interfaces, the proxy class would be restricted fromimplementing the other of two particular interfaces that is in adifferent module than the proxy class. One or more embodiments includethe runtime environment exposing the two particular interfaces to theproxy module using a qualified export, thereby allowing the proxy classin the proxy module to implement both interfaces defined in thedifferent modules than the proxy module. A qualified export exposes thetwo particular interfaces to the proxy module without exposing the twoparticular interfaces to other modules within the module system.Furthermore, the two particular interfaces are exposed to a testframework module which can test the methods of the two particularinterfaces without being able to instantiate the proxy class whichimplements the two particular interfaces. Specifically, the testframework is unable to instantiate the proxy class because the proxyclass, in the proxy module, is not exposed to the test framework module.The test framework module tests the methods of the two particularinterfaces at least by using reflective operations on a proxy object ofthe proxy class type.

5. Miscellaneous; Extensions

Embodiments are directed to a system with one or more devices thatinclude a hardware processor and that are configured to perform any ofthe operations described herein and/or recited in any of the claimsbelow.

In an embodiment, a non-transitory computer readable storage mediumcomprises instructions which, when executed by one or more hardwareprocessors, causes performance of any of the operations described hereinand/or recited in any of the claims.

Any combination of the features and functionalities described herein maybe used in accordance with one or more embodiments. In the foregoingspecification, embodiments have been described with reference tonumerous specific details that may vary from implementation toimplementation. The specification and drawings are, accordingly, to beregarded in an illustrative rather than a restrictive sense. The soleand exclusive indicator of the scope of the invention, and what isintended by the applicants to be the scope of the invention, is theliteral and equivalent scope of the set of claims that issue from thisapplication, in the specific form in which such claims issue, includingany subsequent correction.

6. Hardware Overview

According to one embodiment, the techniques described herein areimplemented by one or more special-purpose computing devices. Thespecial-purpose computing devices may be hard-wired to perform thetechniques, or may include digital electronic devices such as one ormore application-specific integrated circuits (ASICs) or fieldprogrammable gate arrays (FPGAs) that are persistently programmed toperform the techniques, or may include one or more general purposehardware processors programmed to perform the techniques pursuant toprogram instructions in firmware, memory, other storage, or acombination. Such special-purpose computing devices may also combinecustom hard-wired logic, ASICs, or FPGAs with custom programming toaccomplish the techniques. The special-purpose computing devices may bedesktop computer systems, portable computer systems, handheld devices,networking devices or any other device that incorporates hard-wiredand/or program logic to implement the techniques.

For example, FIG. 6 is a block diagram that illustrates a computersystem 600 upon which an embodiment of the invention may be implemented.Computer system 600 includes a bus 602 or other communication mechanismfor communicating information, and a hardware processor 604 coupled withbus 602 for processing information. Hardware processor 604 may be, forexample, a general purpose microprocessor.

Computer system 600 also includes a main memory 606, such as a randomaccess memory (RAM) or other dynamic storage device, coupled to bus 602for storing information and instructions to be executed by processor604. Main memory 606 also may be used for storing temporary variables orother intermediate information during execution of instructions to beexecuted by processor 604. Such instructions, when stored innon-transitory storage media accessible to processor 604, rendercomputer system 600 into a special-purpose machine that is customized toperform the operations specified in the instructions.

Computer system 600 further includes a read only memory (ROM) 608 orother static storage device coupled to bus 602 for storing staticinformation and instructions for processor 604. A storage device 610,such as a magnetic disk or optical disk, is provided and coupled to bus602 for storing information and instructions.

Computer system 600 may be coupled via bus 602 to a display 612, such asa cathode ray tube (CRT), for displaying information to a computer user.An input device 614, including alphanumeric and other keys, is coupledto bus 602 for communicating information and command selections toprocessor 604. Another kind of user input device is cursor control 616,such as a mouse, a trackball, or cursor direction keys for communicatingdirection information and command selections to processor 604 and forcontrolling cursor movement on display 612. This input device typicallyhas two degrees of freedom in two axes, a first axis (e.g., x) and asecond axis (e.g., y), that allows the device to specify positions in aplane.

Computer system 600 may implement the techniques described herein usingcustomized hard-wired logic, one or more ASICs or FPGAs, firmware and/orprogram logic which in combination with the computer system causes orprograms computer system 600 to be a special-purpose machine. Accordingto one embodiment, the techniques herein are performed by computersystem 600 in response to processor 604 executing one or more sequencesof one or more instructions contained in main memory 606. Suchinstructions may be read into main memory 606 from another storagemedium, such as storage device 610. Execution of the sequences ofinstructions contained in main memory 606 causes processor 604 toperform the process steps described herein. In alternative embodiments,hard-wired circuitry may be used in place of or in combination withsoftware instructions.

The term “storage media” as used herein refers to any non-transitorymedia that store data and/or instructions that cause a machine tooperation in a specific fashion. Such storage media may comprisenon-volatile media and/or volatile media. Non-volatile media includes,for example, optical or magnetic disks, such as storage device 610.Volatile media includes dynamic memory, such as main memory 606. Commonforms of storage media include, for example, a floppy disk, a flexibledisk, hard disk, solid state drive, magnetic tape, or any other magneticdata storage medium, a CD-ROM, any other optical data storage medium,any physical medium with patterns of holes, a RAM, a PROM, and EPROM, aFLASH-EPROM, NVRAM, any other memory chip or cartridge.

Storage media is distinct from but may be used in conjunction withtransmission media. Transmission media participates in transferringinformation between storage media. For example, transmission mediaincludes coaxial cables, copper wire and fiber optics, including thewires that comprise bus 602. Transmission media can also take the formof acoustic or light waves, such as those generated during radio-waveand infra-red data communications.

Various forms of media may be involved in carrying one or more sequencesof one or more instructions to processor 604 for execution. For example,the instructions may initially be carried on a magnetic disk or solidstate drive of a remote computer. The remote computer can load theinstructions into its dynamic memory and send the instructions over atelephone line using a modem. A modem local to computer system 600 canreceive the data on the telephone line and use an infra-red transmitterto convert the data to an infra-red signal. An infra-red detector canreceive the data carried in the infra-red signal and appropriatecircuitry can place the data on bus 602. Bus 602 carries the data tomain memory 606, from which processor 604 retrieves and executes theinstructions. The instructions received by main memory 606 mayoptionally be stored on storage device 610 either before or afterexecution by processor 604.

Computer system 600 also includes a communication interface 618 coupledto bus 602. Communication interface 618 provides a two-way datacommunication coupling to a network link 620 that is connected to alocal network 622. For example, communication interface 618 may be anintegrated services digital network (ISDN) card, cable modem, satellitemodem, or a modem to provide a data communication connection to acorresponding kind of telephone line. As another example, communicationinterface 618 may be a local area network (LAN) card to provide a datacommunication connection to a compatible LAN. Wireless links may also beimplemented. In any such implementation, communication interface 618sends and receives electrical, electromagnetic or optical signals thatcarry digital data streams representing various types of information.

Network link 620 typically provides data communication through one ormore networks to other data devices. For example, network link 620 mayprovide a connection through local network 622 to a host computer 624 orto data equipment operated by an Internet Service Provider (ISP) 626.ISP 626 in turn provides data communication services through the worldwide packet data communication network now commonly referred to as the“Internet” 628. Local network 622 and Internet 628 both use electrical,electromagnetic or optical signals that carry digital data streams. Thesignals through the various networks and the signals on network link 620and through communication interface 618, which carry the digital data toand from computer system 600, are example forms of transmission media.

Computer system 600 can send messages and receive data, includingprogram code, through the network(s), network link 620 and communicationinterface 618. In the Internet example, a server 630 might transmit arequested code for an application program through Internet 628, ISP 626,local network 622 and communication interface 618.

The received code may be executed by processor 604 as it is received,and/or stored in storage device 610, or other non-volatile storage forlater execution.

In the foregoing specification, embodiments of the invention have beendescribed with reference to numerous specific details that may vary fromimplementation to implementation. The specification and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense. The sole and exclusive indicator of the scope of the invention,and what is intended by the applicants to be the scope of the invention,is the literal and equivalent scope of the set of claims that issue fromthis application, in the specific form in which such claims issue,including any subsequent correction.

What is claimed is:
 1. A non-transitory computer readable mediumcomprising instructions which, when executed by one or more hardwareprocessors, cause performance of operations comprising: identifying arequest, for a proxy object, comprising a plurality of class objectsrepresenting a plurality of interfaces; generating a proxy class basedon the plurality of class objects; generating or selecting a particularmodule, in a module system, to include the proxy class.
 2. The medium ofclaim 1, wherein the operations are performed by a runtime environment.3. The medium of claim 1, wherein the operations comprise generating theparticular module for the proxy class.
 4. The medium of claim 1, whereinthe operations comprise generating the particular module for the proxyclass by defining a module descriptor that (a) corresponds to theparticular module and (b) does not export any package that includes theproxy class.
 5. The medium of claim 1, wherein the operations compriseselecting the particular module, for the proxy class, from a set ofmodules defined by the module system.
 6. The medium of claim 1, whereinthe operations comprise instantiating the proxy class to generate theproxy object.
 7. The medium of claim 1, wherein the operations furthercomprise providing a proxy object in response to the request for theproxy object.
 8. The medium of claim 1, wherein the plurality of classobjects correspond to a respective plurality of modules which includethe respective plurality of interfaces.
 9. The medium of claim 8,wherein the operations further comprise defining a module descriptor ofthe particular module to include an explicit dependency on each of theplurality of modules.
 10. The medium of claim 8, wherein the operationsfurther comprise modifying a configuration of the plurality of modulesfrom (a) not exposing the plurality of interfaces to the particularmodule to (b) exposing the plurality of interfaces to the particularmodule.
 11. The medium of claim 1, wherein the request is received froma test framework module, and wherein the operations further comprisemodifying a configuration of the plurality of modules from (a) notexposing the plurality of interfaces to the test framework module to (b)exposing the plurality of interfaces to the test framework module. 12.The medium of claim 1, wherein the request specifies a method callprocessor object and wherein the proxy class implements the plurality ofinterfaces with the use of the method call processor object.
 13. Amethod comprising: identifying a request, for a proxy object, comprisinga plurality of class objects representing a plurality of interfaces;generating a proxy class based on the plurality of class objects;generating or selecting a particular module, in a module system, toinclude the proxy class; wherein the method is performed by at least onedevice including a hardware processor.
 14. The method of claim 13,wherein the operations comprise instantiating the proxy class togenerate the proxy object.
 15. The method of claim 13, wherein theplurality of class objects correspond to a respective plurality ofmodules which include the respective plurality of interfaces.
 16. Themethod of claim 15, wherein the operations further comprise defining amodule descriptor of the particular module to include an explicitdependency on each of the plurality of modules.
 17. The method of claim15, wherein the operations further comprise modifying a configuration ofthe plurality of modules from (a) not exposing the plurality ofinterfaces to the particular module to (b) exposing the plurality ofinterfaces to the particular module.
 18. The method of claim 13, whereinthe request is received from a test framework module, and wherein theoperations further comprise modifying a configuration of the pluralityof modules from (a) not exposing the plurality of interfaces to the testframework module to (b) exposing the plurality of interfaces to the testframework module.
 19. The method of claim 13, wherein the requestspecifies a method call processor object and wherein the proxy classimplements the plurality of interfaces with the use of the method callprocessor object.
 20. A system comprising: at least one device includinga hardware processor; the system being configured to perform operationscomprising: identifying a request, for a proxy object, comprising aplurality of class objects representing a plurality of interfaces;generating a proxy class based on the plurality of class objects;generating or selecting a particular module, in a module system, toinclude the proxy class.